System of electric lighting.



No. 738,113. PATENTED SEPT. 1, 1903.. H. LEITNER & R. N. LUCAS.

SYSTEM OF ELECTRIC LIGHTING.

APPLIOATIOR' FILED DBO. 22, 1902.

HO MODEL.

a lml filmmw Mam/1mm jammy pwe'hmkzrywwv gukmk MW M V UNITED STATES Patented S$eptember 1,1903.

PATENT OFFICE.

nanny LEITNER, or WOKING, AND RICHARD NORMAN- LUCAS, or

BYFLEET, ENGALND.

SYSTEM or ELECTRIC LIGHTING.

SPECIFICATION ifortnningpart of Letters Patent.No. 788,113, dated September 1, 1903. Application'iiied December 22, 1902. Serial No. 136,267. (No model.)

To all whom, it may concern:

Be it known that we, HENRY LnrrNEn, residing at Mayhury, Voking, and RICHARD NORMAN LUCAS, residing at Rose Villa, Byfieet, Surrey, England, both subjects of the King of Great Britain',have invented new and useful improvements in Systems of Electric Lighting, of which the following is a specifi cation;

O'urin vention has reference to an improved system of lighting railway-trains in which current is obtained from a dynamo driven from one of the axles of the vehicle and adapted to charge a battery of accumulators mounted on it. It has special reference to systems in which two dynamos mounted on the same shaft with one another are arranged so as to neutralize the effect of increased speed in raising the voltage and give within certain limits an approximately constant voltage and current,no matter what the speed may be. In such systems where one dynamo is employed to weaken the field of another dynamo (the main generator) as the speed increases we have found that difficulties are encountered in'keeping the voltage constant and thatin consequence when arranged to charge a battery of accumulators such a combination gives too high a current at intermediate speeds of the train and too low a current when the speed becomes increased beyond a of the two machines increases; but'we prefer to provide the field of the subsidiary or-demagnetizing dynamowith a series winding through which the exciting-current of the shunt-winding of the main dynamo passes, this series winding being in series with it and with the armature of the subsidiary dynamo or demagnetizirig-machine, so that the shunt-current of. the main dynamo passes both through the armature of the subsidiary dynamo and through its series winding in addition to energizing the shunt-winding of the main machine; The main generator itself is preferably provided with a differential series Winding tending to reducethe magnetisrn of its field'or fields when current passes through it, and through this winding we take the current generated by the main generator when charging the cells. The sh nut-winding of the subsidiary dynamo,which provides the demagnetizing effect, is under the normalworking of the system arranged. across the terminals of the main generator. The series winding on the field-magnet of-the demagnetizing machine assists the magnetism produced by the shunt-winding, in this respect differing from the series winding'of the g'enorator, which diminishes the field magnetism of the machine. In order to increase the range of the combination, it is necessary that the current passing through the shunt-winding of the main generator should be diminished'whenever the voltage of that machine tends to rise to agreater extent than the action of the demagnetizing or subsidiary dynamo alone would reduce itand diminished less thereby when the main generator tends to fall.

We effect this partly by intro-- du'cing in series with the shunt-winding of the demagneizing-machine a carbon resistance, preferably in the form of one or more incandescent lamps. We select carbon for this purpose, as it has a negative temperature coeflicient-that is to say, its resistance tends to diminish as its temperature increases; but we may employ instead of it any other convenient material having that characteris- .ticas, for'ex aniple, sultid of iron.

In addition we provide a second path for the current of the shunt or fine'wire winding of the main generator preferablyata point between one end of the shunt-winding and the series winding on the demag'netizer---bya resistance having, a positive temperatuge coefficient. For this purpose we prefer to use iron wire. As a further means of diminishingthe tendency to rise of voltage in the main dynamo 'we introduce in series with-its shun-t or tinewire winding' an additional'resistance with positive temperature coelficient, also preferably of i you wire. The elfect of this resistance may be increased byarranging it so as to be heated by the main current of the dynamo, which is led through a resistance-wire in close prox-. imity to this iron-wire resistance in series with the shunt-winding of the generator-field. The action is then such that if the dynamocurrent rises it increases the resistance of the said iron-wire resistance 'in series with the shunt-winding by increasingits temperature beyond that which it attains owing to the current passing directly through it.

In connection with the above-described appliances we employ a self-acting device for switching in the dynamo into the batterycircuit, so as to charge the latter when its Voltage has risen to the required amount and for breaking theconnection between the battery andthe dynamo when the voltage of the battery exceeds that of the latter. This automatic switch may also be arrangedso as to only introduce normal current to the principal'winding of the demagnetizer-field after the main dynamo has excited.

The self-acting switch or cut-out which we prefer to errtploy consists of a field-magnet arranged like the field of a motor and of an armature provided with a fine-wire winding. The field-magnet is provided with a high-resistance fine-wire and a low-resistance.

coarse-wire winding, and the armature, on the shaft of which are mounted. two or more sets of contacts, is normally heldin its off position by arsnitable spring. The fine-wire winding of the armature is arranged in series with the fine-wirewindiqg of the field of the cut-out, and both are arranged to be energ'ized by the maine'nerator current. When the generator ex'ites itself and before the cut-out has executed its first movement, owing to the action of the curreutsnpplied to it thereby, the current from the generator passes through the fine wire-winding of the field of the cut-out and then divides, part flowing through. the winding on the cnt-out armature and part passing through the shuntwinding of the demagnetizing-dynamo. The fie of the dcmagnetizer isnnder these circumstances very feebly magnetized, owing to the high-resistance fine-wire windingof the cut-out field "being in series with it.

In order'that our invention may he more readily understood, we refer to the accompanying diagrammatic drawing,.which wehereby make part of this specification.

In the drawing, a is'the shunt or fine-wire field-winding of the main generator, b being the corresponding fine-wire field-winding of the demagnetizing-dynamo.

0 is the series winding, through which the main current of ,the generator passes, d being the series winding of the .demagnetizer.

e and frepresent the comm utators, brushes,

and armatures of the main generator and de magnetizing-dynamo, respectively, which are h is the carbon resistance or incandescent lamp in series with the fine-wire'field-winding of the demagnetizer. Only one such resistance is shownin the drawing, but we may employ several in parallel or series with one another.

t' isthe resistance with positive temperatu re coeflicient arranged across the main-generator field and armature in the manner shown, so that some of the current-flowing through the fine wire field-winding a may pass through it;

a is the iron-wire resistance in series with the fine-wire field-winding a, arranged around, preferably insulated from, and adapted to be heated by the generator-current when passing to the battery of accumulators 9 through the resistance-wire or heating-coil a Z is the fine-wire high-resistance winding of the balanced armature of the device or cutout for switching in the dynamo into the accumulator-circuit, so as to charge the battery of accumulators g. The shaft of this armat'ure carries at its end two cylindersprovided with the contactpieceso 0 and p p for bridgthe series winding 0 on its field, the resistance-wire a andthen through the high-resis'tance windi-ngj of the cut-out, after which it branches, part flowing through the armature-winding lof the cut-out baQzk by the path 1' and L and part passing through the lamph and the'fine-wire field-winding b of the demagnetizing-dynamo to. the other brush of the main dynamo. The elfect produced by this field 'winding b is under these circumstances very small, as the high. resistancej' is then in series with it. 4

When the field of the-cut-out and its armature have both been energized by the current passing through j and Z, the armature revolves against the-action of the spring, the'contactpieces 0 0 bridging the gap m m. controlling the movements of the armature of the cut-out is so adj usted. that this movement does not take place until the voltage of the generator is'in excess of the battery 9.-

When the cut-out has turned so as to bridge the gap m m, the current then flows from the generator through the winding j to the cells,

charging them with a feeblecurrent owing tothe high resistance of Z. 1 At the same time the field-winding I of the subsidiary dynamp' is Thespring- 45 those means alone be kept suiliciently. con- 'ance of h were a constant quantity.

connected through the lamp h to the battery 9 and receives normal current.

When the voltage of the dynamo increases the armature of the cut-out may be prevented by a stop 25, as shown. When the gap n 'n. is closed, the chargingcurrent passes mainly through the thick-wire winding 1;, thereby strengthening the field of the cut-out and causing it to act after the manner of a holding-down relay.

(hen owing to the speed of the generator diminishing its voltage sinks to that of the battery of accumulators g, current ceases to pass through either of the ileld-windingsj or 7r, of the cut-out and the spring restores it to its normal position, breaking the gaps or n and mm and severing connection between the generator and the battery. It the voltage of the dynamo sinks very rapidly to below that of the battery, a momentary reversal of current in the cut-out windings j and it? takes place,'causing a reversal of magnetism in its field and assisting the spring in turning back its armature to zero position and breaking the gaps.

As in other similar arrangements the opposing electromotive force produced by the demagnetizing-dynamo tends to weaken-the current flowing through the fine-wire fieldwinding a of thegenerator. The effect thus produced is at different speeds, sometimes too great and sometimes too small,and though this is to a large extent corrected by the series demagnetizing field-winding u on the generator, through which the main current flows and which tends to weaken its field, the resulting voltage and current cannot by staut over the wide range of speed involved in train-lighting. Such constancy, however, is obtained by the action of the carbon-lamp resistance h and the iron-wire resistance *5 and a.

When the voltage of the generator rises or tends to. rise, more current tends to pass through-the lamp h and the fine-wire winding 1) of the demagnetizer. This extra current increases the temperature of the carbon of the lamp or lamps h and reduces its resistance, thereby permitting a greater increase of current to flow through the winding 1) than would take place if the resist The field of the demagnetizer isconsequently disproportionately strengthened, and it tends to reduce the current in the fine-wire winding a of the generator disproportionately.

Similarly,if the voltage .of the generator falls [or tends to fail less current passes both through the fine-wire field-winding-of the demagnetizcr and the lamp or lamps h, and

' the resistance of the latter thereupon increases, weakening the, magnetic field of-the demagnetizer more than it would be weak: ened if the resistance of h remain constant.

is produced by the positive temperaturecoefficient (iron wire) resistance a. The excitof the generator passes both through the ar mature f and seriesfield-winding d ofthe demagnetize'r and through the resistancei in parallel. It now the voltage at the terminals of the generator rises or tends to rise, the portion of exciting-current which flows through Z ture, and in consequence its resistance, the result being' that more resistance is interposed to the passage of that portion of the exciting-current which flows through than would be the case if the resistance of '11 remained constant. The result is to weaken the field ofthegenerator. SimilarlyQ'if the voltage oft-he generator falls or tends to fall less current passes through the resistance 2', itstemperatu're sinks, and its resistance diminishes, allowing more current to pass through the field-winding a and opposing'the tendency to weaken its field. The function of the resistance a, in series with the fieldwinding a is similar. the generator to the accumulators passing through the resistance 09, the resistance of which is suitably proportioned, increases, it heats 0: and by juxtaposition also heats a.

by diminishes or tends to diminish the cur.- rent in the field-winding a. Correspondingly, if the current of the generator sinks the temperature of (1 falls and that of aal'so diminishes. Its resistance, therefore, decreases and lnore'current flows or tends to flow through the field nvinding a, thereby strengthening the field of the generator and tending to raise its voltage or current."

ploying all three of these arrangementsnamely, aresistance with negative tempera ture coeflicien-t (carbon) inseries with the fine-wire winding of the demagnetizing-dynawire) in shunt with the demagnetizer, and a resistance with positive temperature coeflicient (iron wire) adapted to be heated by the current from the main generator; but it will be understeod that we may without departing from the spirit or scope of our invention use any one or two of -these devices without employing them all at the same time.

tor and dcmagnetizing-dynamo are provided with series field-windi u gs connected as shown and mounted on the same shaft, as we have When the currentfrom' This increases the resistance of a, and there- \Ve have described ourinvention as em mo, a resistance with positive coefficient (iron- A corresponding efiect in the same direction ing-current to the fine-wire field-winding a tends to increase. This increases its tempera- Similarly, we have shown our invention applied to a system in which both the main generafound that this gives the best practical results; but the invention may also be applied in a system in which neither the main generator nor dem'agnetizer are provided with series windings or in a system in which neither or only one of them is so constructed andthe subsidiary dynamo driven at a speed bearing a fixed proportion to that of the main generator; We have also described the effect of the resistance t merely as it influences the voltage of the main generator; but-it, also subserves another useful purpose-nam'ely, that of facilitating the excitation of the main generator by providing a path for the current to the field-winding a by which it can pass without traversing the armature'and commutator of the demagnetizing-dynamo, the resistance of i, asits temperature is then low, being small. Similarly, we have described the self-acting switch as merely closing two gaps in the manner and for the purposes set forth; but we may also adapt it to insert or cut out resistance between the accu mulators and the lamp-circuit according as the generator is or is not furnishing current,

Likewise we have described in the above combination a form of cut-in and cut-out device which has special advantages, as the moving part consists of a balanced armature and is therefore peculiarly suited for use in -the lighting of railway-trains; but it will be understood that we may employ instead of it any other suitable form of cut-out that will cut out the dynamo from connection with the accutn ulator-circuit when its voltage sinks ed to weaken the field or fields of the main generator as thespeed of driving increases, the combinationtherewith of a resistance having a negative; temperature coefficient,

arranged in series with the shunt or fine=wire winding of the subsidiary dynamo, of a resist-ance having a positive temperature coefficie'n't, adapted to be heated by the maingenerator' current, and arranged in series with the shunt or fine-w.ire winding of-the main generator, and of a resistance havinga --positive temperature coefiicient arranged in shunt with the subsidiary or demagnetizing Having now particulariydescribed and as certained the nature of our said invention dynamo for the purposes set forth and de scribed.

2. In a system of electric lighting by means of a main generator ordynamo driven at vahavinga negative temperature coefiicient arranged in series with the shunt or fine-wire Winding of the subsidiary dynamo,vand of a resistance having a positive temperature coefficient and adapted to be heated by the maingenerator current, and arranged in series with the shunt or finewire winding of the main generator, for the purposes set forth and described. 1

3. In a system of electric lighting by means of a main generator or dynamo driven at variable speed, and a subsidiary dynamo driven at the same or proportional speed, and adapted to weaken the fields of the main generator. as the speed of driving increases, the combination therewith of a resistance having, a negative. temperature coefiicient arranged in series with the shunt or fine-wire winding of the subsidiary dynamo, for the purposes set forth and described.

4. In a system of electric lighting by means of a main generator or dynamo driven at variable speed, and a subsidiary dynamo driven at the same or proportional speed, and adapt- .ed to weaken the field or fields of the main generator as the speed of driving increases, the combination therewith of a self-acting switch comprising a magnetic field with finewire and coarse-wire windings, a movable armature, and movable contact-pieces adapted to be operated by the latter so as to bridge successively twogaps in the system, the said self-acting switch being arranged in the circuitin such a manner that when the generator excites itself, the switch closes one gap, thereby permitting the fine-wire field-winding of the demagnetizing-dynamo to receive normal current while when the speed and yoltage of the generatorrises, the said selfactingswitch closes a second gap through which when closed, the generator-current by f way of the coarsewire winding of the field of the self-acting switch passes to charge the accumulators in the manner described and set forth.

HENRY LEITNER. RICHARD NORMAN LUCAS. Witnesses: I G. G. REDFERN,

A..ALBUT'r; 

